U.S. patent number 11,178,434 [Application Number 16/505,478] was granted by the patent office on 2021-11-16 for transmission apparatus, transmission method, reception apparatus, and reception method.
This patent grant is currently assigned to SONY CORPORATION. The grantee listed for this patent is SONY CORPORATION. Invention is credited to Ikuo Tsukagoshi.
United States Patent |
11,178,434 |
Tsukagoshi |
November 16, 2021 |
Transmission apparatus, transmission method, reception apparatus,
and reception method
Abstract
Reception-side processing performed in a case where transmission
of standard dynamic range video data and transmission of high
dynamic range video data coexist in a time sequence is simplified.
SDR transmission video data is converted into SDR transmission
video data through dynamic range conversion. The SDR transmission
video data is the one obtained by performing, on SDR video data,
photoelectric conversion in accordance with an SDR photoelectric
conversion characteristic. In this case, the conversion is
performed on the basis of conversion information for converting a
value of conversion data in accordance with the SDR photoelectric
conversion characteristic into a value of conversion data in
accordance with an HDR photoelectric conversion characteristic. A
video stream is obtained by performing encoding processing on HDR
transmission video data. A container having a predetermined format
and including this video stream is transmitted.
Inventors: |
Tsukagoshi; Ikuo (Tokyo,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
SONY CORPORATION |
Tokyo |
N/A |
JP |
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Assignee: |
SONY CORPORATION (Tokyo,
JP)
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Family
ID: |
1000005937063 |
Appl.
No.: |
16/505,478 |
Filed: |
July 8, 2019 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20190335211 A1 |
Oct 31, 2019 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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15544285 |
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10390057 |
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PCT/JP2016/053858 |
Feb 9, 2016 |
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Foreign Application Priority Data
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Feb 17, 2015 [JP] |
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JP2015-029106 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04N
21/2343 (20130101); H04N 19/85 (20141101); H04N
21/236 (20130101); H04N 21/4402 (20130101); H04N
19/70 (20141101); H04N 21/434 (20130101) |
Current International
Class: |
H04N
21/2343 (20110101); H04N 21/434 (20110101); H04N
21/236 (20110101); H04N 21/44 (20110101); H04N
19/70 (20140101); H04N 19/85 (20140101); H04N
21/4402 (20110101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2013-543290 |
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Nov 2013 |
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JP |
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2014-534719 |
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Dec 2014 |
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JP |
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2015-8361 |
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Jan 2015 |
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JP |
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WO2015/072754 |
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May 2015 |
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WO |
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Other References
Office Action dated Dec. 17, 2019 in corresponding Japanese Patent
Application No. 2017-500620, 5 pages. cited by applicant .
Tim Borer, "Non-linear Opto-Electrical Transfer Functions for High
Dynamic Range Television," BBC Research & Development White
Paper WHP 283, British Broadcasting Corporation , Jul. 2014 (23
pages). cited by applicant .
International Search Report dated Apr. 26, 2016 in
PCT/JP2016/053858 filed Feb. 9, 2016. cited by applicant .
Author: Society of Motion Picture and Television Engineers (SMPTE);
Title: Study Group Report High-Dynamic-Range (HDR) Imaging
Ecosystem; Date: Sep. 19, 2015 (Year: 2015). cited by applicant
.
Author: T. Borer and A. Cotton of British Broadcasting Corporation
(BBC): Title: WHP 309, A "Display Independent" High Dynamic Range
Television System; Date: Sep. 2015 (Year: 2015). cited by applicant
.
Office Action dated Jul. 14, 2020 in corresponding Japanese Patent
Application No. 2017-500620, 3 pages. cited by applicant.
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Primary Examiner: Saltarelli; Dominic D
Attorney, Agent or Firm: Oblon, McClelland, Maier &
Neustadt, L.L.P.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation of U.S. application Ser. No.
15/544,285, filed on Jul. 18, 2017, which is a U.S. National Phase
of International Patent Application No. PCT/JP2016/053858 filed on
Feb. 9, 2016, which claims priority benefit of Japanese Patent
Application No. JP 2015-029106 filed in the Japan Patent Office on
Feb. 17, 2015. Each of the above-referenced applications are
incorporated herein by reference in its entirety.
Claims
The invention claimed is:
1. A transmission apparatus comprising: processing circuitry
configured to obtain first dynamic range transmission video data by
applying a first photoelectric conversion characteristic to first
dynamic range video data, convert the first dynamic range
transmission video data to second dynamic range transmission video
data based on conversion information for converting a value of
conversion data in accordance with the first photoelectric
conversion characteristic into a value of conversion data in
accordance with a second photoelectric conversion characteristic,
obtain a video stream by performing encoding processing on the
second dynamic range transmission video data, and insert, into the
video stream, the conversion information used to convert the first
dynamic range transmission video data to the second dynamic range
transmission video data; and a transmitter configured to transmit
the video stream including the conversion information and to
transmit metadata including information indicating an
electro-optical transfer function corresponding to the second
photoelectric conversion characteristic.
2. The transmission apparatus according to claim 1, wherein a first
dynamic range of the first dynamic range transmission video data is
a standard dynamic range, and a second dynamic range of the second
dynamic range transmission video data is a high dynamic range.
3. The transmission apparatus according to claim 1, wherein the
processing circuitry is further configured to: obtain the second
dynamic range transmission video data by converting from a color
space to a luminance and chrominance domain.
4. The transmission apparatus according to claim 1, wherein the
metadata includes information indicating a dynamic range of the
video stream.
5. The transmission apparatus according to claim 1, wherein the
metadata further includes information indicating color primaries
for the video stream.
6. The transmission apparatus according to claim 5, wherein the
metadata further includes information indicating color matrix
coefficient for the video stream.
7. The transmission apparatus according to claim 1, wherein the
metadata includes information indicating an original dynamic range
of the video stream.
8. The transmission apparatus according to claim 1, wherein the
conversion information is a conversion coefficient.
9. The transmission apparatus according to claim 1, wherein the
conversion information is a conversion table.
10. The transmission apparatus according to claim 1, wherein the
conversion information comprises a data structure, including the
metadata indicating the electro-optical transfer function
corresponding to the second photoelectric conversion characteristic
as one of plural elements of the data structure.
11. A transmission method comprising: obtaining first dynamic range
transmission video data by applying a first photoelectric
conversion characteristic to first dynamic range video data;
converting the first dynamic range transmission video data to
second dynamic range transmission video data based on conversion
information for converting a value of conversion data in accordance
with the first photoelectric conversion characteristic into a value
of conversion data in accordance with a second photoelectric
conversion characteristic; obtaining a video stream by performing
encoding processing on the second dynamic range transmission video
data; inserting, into the video stream, the conversion information
used to convert the first dynamic range transmission video data to
the second dynamic range transmission video data; and transmitting
via a transmitter, the video stream including the conversion
information and transmitting metadata including information
indicating an electro-optical transfer function corresponding to
the second photoelectric conversion characteristic.
12. A reception apparatus comprising: a receiver configured to
receive a video stream of encoded second dynamic range transmission
video data, the video stream further including conversion
information used to convert first dynamic range transmission video
data having a first photoelectric conversion characteristic to the
second dynamic range transmission video data having a second
photoelectric conversion characteristic, and to receive metadata
including information indicating an electro-optical transfer
function corresponding to the second photoelectric conversion
characteristic; and processing circuitry configured to, obtain the
second dynamic range transmission video data by performing decoding
processing on the video stream, extract the conversion information
from the video stream, obtain the first dynamic range transmission
video data by performing dynamic range conversion on the second
dynamic range transmission video data based on the conversion
information extracted from the video stream, and display first
dynamic range video data by performing, on the first dynamic range
transmission video data, electro-optical conversion in accordance
with a first electro-optical conversion characteristic.
13. The reception apparatus according to claim 12, wherein the
second dynamic range transmission video data is obtained by
performing the dynamic range conversion on the first dynamic range
transmission video data based on the conversion information for
converting a value of conversion data in accordance with the first
photoelectric conversion characteristic into a value of conversion
data in accordance with the second photoelectric conversion
characteristic, the first dynamic range transmission video data
being obtained by performing, on first dynamic range video data,
photoelectric conversion in accordance with the first photoelectric
conversion characteristic.
14. The reception apparatus according to claim 13, wherein the
second dynamic range transmission video data is obtained by
converting from a color space to a luminance and chrominance
domain.
15. The reception apparatus according to claim 12, wherein a first
dynamic range of the first dynamic range transmission video data is
a standard dynamic range and a second dynamic range of the second
dynamic range transmission video data is a high dynamic range.
16. The reception apparatus according to claim 12, wherein the
metadata includes information indicating a dynamic range of the
video stream.
17. The reception apparatus according to claim 16, wherein the
metadata further includes information indicating color primaries
for the video stream.
18. The reception apparatus according to claim 17, wherein the
metadata further includes information indicating color matrix
coefficient for the video stream.
19. The reception apparatus according to claim 12, wherein the
metadata includes information indicating an original dynamic range
of the video stream.
20. A reception method comprising: receiving, by a receiver, a
video stream of encoded second dynamic range transmission video
data, the video stream further including conversion information
used to convert first dynamic range transmission video data having
a first photoelectric conversion characteristic to the second
dynamic range transmission video data having a second photoelectric
conversion characteristic, and receiving metadata including
information indicating an electro-optical transfer function
corresponding to the second photoelectric conversion
characteristic; obtaining the second dynamic range transmission
video data by performing decoding processing on the encoded second
dynamic range transmission video data included in the video stream;
extracting the conversion information from the video stream,
obtaining the first dynamic range transmission video data by
performing dynamic range conversion on the second dynamic range
transmission video data based on the conversion information
extracted from the video stream; and displaying first dynamic range
video data by performing, on the first dynamic range transmission
video data, electro-optical conversion in accordance with a first
electro-optical conversion characteristic.
Description
TECHNICAL FIELD
The present technology relates to a transmission apparatus, a
transmission method, a reception apparatus, and a reception method,
and particularly, to a transmission apparatus or the like that
transmits standard dynamic range video data.
BACKGROUND ART
Conventionally, it has been considered to transmit transmission
video data obtained by applying high dynamic range photoelectric
conversion to high dynamic range video data. Hereinafter, a high
dynamic range is appropriately referred to as "HDR". For example,
there is a description about an HDR photoelectric conversion
characteristic (new gamma characteristic) in Non-Patent Document 1.
The HDR photoelectric conversion characteristic includes a region
compatible with a conventional photoelectric conversion
characteristic (gamma characteristic), taking into account
reception by a conventional receiver.
CITATION LIST
Non-Patent Document
Non-Patent Document 1: Tim Borer, "Non-Linear Opto-Electrical
Transfer Functions for High Dynamic Range Television", Research
& Development White Paper WHP 283, July 2014
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
An object of the present technology is to simplify reception-side
processing performed in a case where transmission of standard
dynamic range video data and transmission of high dynamic range
video data are performed by a single transmission method.
Solutions to Problems
A concept of the present technology lies in a transmission
apparatus including:
a dynamic range conversion unit configured to obtain high dynamic
range transmission video data by performing dynamic range
conversion on standard dynamic range transmission video data on the
basis of conversion information for converting a value of
conversion data in accordance with a standard dynamic range
photoelectric conversion characteristic into a value of conversion
data in accordance with a high dynamic range photoelectric
conversion characteristic, the standard dynamic range transmission
video data being obtained by performing, on standard dynamic range
video data, photoelectric conversion in accordance with the
standard dynamic range photoelectric conversion characteristic;
an encoding unit configured to obtain a video stream by performing
encoding processing on the high dynamic range transmission video
data; and
a transmission unit configured to transmit a container having a
predetermined format and including the video stream.
According to the present technology, the dynamic range conversion
unit can obtain the high dynamic range transmission video data by
performing the dynamic range conversion on the standard dynamic
range transmission video data obtained by performing, on the
standard dynamic range video data, the photoelectric conversion in
accordance with the standard dynamic range photoelectric conversion
characteristic. In such a case, the conversion is performed on the
basis of the conversion information for converting the value of the
conversion data in accordance with the standard dynamic range
photoelectric conversion characteristic into the value of the
conversion data in accordance with the high dynamic range
photoelectric conversion characteristic. For example, the
conversion information may be of a conversion coefficient or a
conversion table.
The encoding unit can obtain the video stream by performing the
encoding processing on the high dynamic range transmission video
data. The transmission unit transmits the container having the
predetermined format and including this video stream. For example,
the container may be MP4 used for the Internet distribution or the
like, a transport stream (MPEG-2 TS) adopted by a digital
broadcasting standard, or a container in any other format.
According to the present technology as described above, the
standard dynamic range transmission video data is transmitted after
being converted into the high dynamic range transmission video
data. Even when transmitting the standard dynamic range video data,
therefore, the reception side can perform similar processing to
that in transmission of high dynamic range video data. This makes
it possible to simplify the reception-side processing performed in
a case where transmission of the standard dynamic range video data
and transmission of the high dynamic range video data coexist in a
time sequence.
Note that according to the present technology, for example, an
information insertion unit may be further included. The information
insertion unit inserts, into the video stream and/or the container,
the conversion information for converting the value of the
conversion data in accordance with the standard dynamic range
photoelectric conversion characteristic into the value of the
conversion data in accordance with the high dynamic range
photoelectric conversion characteristic. In a case where the
conversion information is inserted as described above, the
reception side can easily perform processing for converting the
high dynamic range transmission video data into the standard
dynamic range transmission video data with this conversion
information and displaying a standard dynamic range image.
Furthermore, according to the present technology, for example, the
information insertion unit may further insert, into the container,
information indicating that the video stream supports a high
dynamic range. This information allows the reception side to easily
recognize that the video stream supports the high dynamic
range.
Furthermore, according to the present technology, for example, the
information insertion unit may further insert, into the container,
information indicating a high dynamic range electro-optical
conversion characteristic corresponding to the high dynamic range
photoelectric conversion characteristic. This information allows
the reception side to easily recognize the high dynamic range
electro-optical conversion characteristic corresponding to the high
dynamic range photoelectric conversion characteristic.
Furthermore, according to the present technology, for example, the
information insertion unit may further insert, into the container,
information indicating that original video data is the standard
dynamic range video data. This information allows the reception
side to easily recognize that the original video data is the
standard dynamic range video data.
Furthermore, another concept of the present technology lies in a
reception apparatus including:
a reception unit configured to receive a container having a
predetermined format and including a video stream obtained by
encoding high dynamic range transmission video data;
a decoding unit configured to obtain the high dynamic range
transmission video data by performing decoding processing on the
video stream;
a dynamic range conversion unit configured to obtain standard
dynamic range transmission video data by performing dynamic range
conversion on the high dynamic range transmission video data
obtained by the decoding unit; and
an electro-optical conversion unit configured to obtain display
standard dynamic range video data by performing, on the standard
dynamic range transmission video data, electro-optical conversion
in accordance with a standard dynamic range electro-optical
conversion characteristic, the standard dynamic range transmission
video data being obtained by the dynamic range conversion unit.
According to the present technology, the reception unit receives
the container having the predetermined format and including the
video stream obtained by encoding the high dynamic range
transmission video data. The decoding unit can obtain the high
dynamic range transmission video data by performing the decoding
processing on the video stream.
The dynamic range conversion unit can obtain the standard dynamic
range transmission video data by performing the dynamic range
conversion on the high dynamic range transmission video data
obtained by the decoding unit. Then, the electro-optical conversion
unit can obtain the display standard dynamic range video data by
performing, on the standard dynamic range transmission video data,
the electro-optical conversion in accordance with the standard
dynamic range electro-optical conversion characteristic.
According to the present technology as described above, the
standard dynamic range transmission video data is obtained by
performing the dynamic range conversion on the high dynamic range
transmission video data obtained by the decoding processing.
Accordingly, even in the case of being transmitted as the high
dynamic range transmission video data, it is possible to display a
standard dynamic range image satisfactorily.
Note that according to the present technology, for example, the
high dynamic range transmission video data obtained by the decoding
unit may be obtained by performing dynamic range conversion
processing on the standard dynamic range transmission video data on
the basis of conversion information for converting a value of
conversion data in accordance with a standard dynamic range
photoelectric conversion characteristic into a value of conversion
data in accordance with a high dynamic range photoelectric
conversion characteristic. The standard dynamic range transmission
video data is obtained by performing, on standard dynamic range
video data, photoelectric conversion in accordance with the
standard dynamic range photoelectric conversion characteristic.
Furthermore, according to the present technology, for example, the
conversion information may be inserted into the video stream and/or
the container. A conversion information extraction unit to extract
the conversion information from the video stream and/or the
container may be further included. The dynamic range conversion
unit may perform dynamic range conversion on the basis of the
conversion information extracted by the conversion information
extraction unit.
Effects of the Invention
According to the present technology, it is possible to simplify
reception-side processing performed in a case where transmission of
standard dynamic range video data and transmission of high dynamic
range video data coexist in a time sequence. Note that the effects
described in this specification are merely examples and not limited
thereto, and additional effects may also be included.
BRIEF DESCRIPTION OF DRAWINGS
FIGS. 1(a) and 1(b) are block diagrams illustrating exemplary
configurations of an MPEG-DASH-based stream distribution
system.
FIGS. 2(a) to 2(e) are diagrams illustrating an example of a
relationship between each of structures hierarchically arranged in
an MPD file.
FIG. 3 is a block diagram illustrating an exemplary configuration
of a transmission and reception system as an embodiment.
FIG. 4 is a block diagram illustrating an exemplary configuration
of a service transmission system.
FIG. 5 is a diagram for describing an operation of a dynamic range
conversion unit in the service transmission system.
FIG. 6 is a diagram illustrating an access unit at the head of a
GOP in a case where an encoding method is HEVC.
FIG. 7 is a diagram illustrating an exemplary structure of a
dynamic range conversion SEI message.
FIG. 8 is a diagram illustrating contents of main information in
the exemplary structure of the dynamic range conversion SEI
message.
FIG. 9 is a diagram for describing a media file entity for a
non-fragmented MP4 (Non-Fragmented MP4) case (VOD service).
FIG. 10 is a diagram for describing a media file entity for a
fragmented MP4 (Fragmented MP4) case (multicast service).
FIG. 11 is a diagram for describing a media file entity for a
fragmented MP4 (Fragmented MP4) case (broadcasting).
FIG. 12 is a diagram illustrating an exemplary description of the
MPD file.
FIG. 13 is a diagram illustrating "Value" semantics of
"SupplementaryDescriptor".
FIG. 14 is a block section illustrating an exemplary configuration
of a service receiver.
FIG. 15 is a diagram for describing details of dynamic range
inverse conversion in a case where original video data of a current
stream is SDR video data.
FIG. 16 is a diagram for describing details of dynamic range
inverse conversion in a case where original video data of a current
stream is HDR video data.
FIG. 17 is a diagram illustrating an exemplary structure of a
dynamic range conversion descriptor.
FIG. 18 is a diagram illustrating contents of main information in
the exemplary structure of the dynamic range conversion
descriptor.
FIG. 19 is a diagram illustrating an exemplary configuration of a
transport stream.
MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a mode for carrying out the invention (hereinafter
referred to as "embodiment") will be described. Note that the
description will be given in the following order.
1. Embodiment
2. Modification
1. Embodiment
[Overview of the MPEG-DASH-Based Stream Distribution System]
First, an overview of an MPEG-DASH-based stream distribution system
to which the present technology can be applied will be
described.
FIG. 1(a) illustrates an exemplary configuration of an
MPEG-DASH-based stream distribution system 30A. In this exemplary
configuration, a media stream and an MPD file are transmitted
through a communication network transmission line (communication
transmission line). This stream distribution system 30A has a
configuration in which N number of service receivers 33-1, 33-2, .
. . , and 33-N are connected to a DASH stream file server 31 and a
DASH MPD server 32 via a content delivery network (CDN) 34.
The DASH stream file server 31 generates a stream segment
conforming to DASH specifications (hereinafter, appropriately
referred to as a "DASH segment") on the basis of media data (video
data, audio data, subtitle data, and the like) of a predetermined
content, and transmits the segment in response to an HTTP request
from the service receiver. This DASH stream file server 31 may be a
server dedicated to streaming or may also be used as a web (Web)
server.
Furthermore, in response to the request for the segment of the
predetermined stream transmitted from the service receiver 33
(33-1, 33-2, . . . , and 33-N) via the CDN 34, the DASH stream file
server 31 transmits the segment of the stream to the receiver,
which is the request source, through the CDN 34. In this case, the
service receiver 33 makes the request by referring to values of
rates described in a media presentation description (MPD) file and
selecting a stream with an optimal rate according to the condition
of a network environment where the client is placed.
The DASH MPD server 32 is a server that generates an MPD file for
obtaining the DASH segment generated in the DASH stream file server
31. The MPD file is generated on the basis of content metadata
transmitted from a content management server (not illustrated) and
an address (url) of the segment generated in the DASH stream file
server 31. Note that the DASH stream file server 31 and the DASH
MPD server 32 may be physically an identical server.
The MPD format uses an element called a representation
(Representation) for each of the streams such as videos and audio
to describe a corresponding attribute. In the MPD file, for
example, the representation is separated for each of a plurality of
video data streams having different rates to describe their
respective rates. The service receiver 33 can refer to the values
of these rates and select an optimal stream according to the
condition of the network environment where the service receiver 33
is placed, as described above.
FIG. 1(b) illustrates an exemplary configuration of an
MPEG-DASH-based stream distribution system 30B. In this exemplary
configuration, a media stream and an MPD file are transmitted
through an RF transmission line (broadcast transmission line). This
stream distribution system 30B includes a broadcast transmission
system 36 to which a DASH stream file server 31 and a DASH MPD
server 32 are connected, and M number of service receivers 35-1,
35-2, . . . , and 35-M.
In the case of this stream distribution system 30B, the broadcast
transmission system 36 transmits a stream segment and an MPD file
on a broadcast wave. The stream segment (DASH segment) conforming
to the DASH specifications is generated by the DASH stream file
server 31. The MPD file is generated by the DASH MPD server 32.
FIGS. 2(a) to 2(e) illustrate an example of a relationship between
each of structures hierarchically arranged in the MPD file. As
illustrated in FIG. 2(a), there exists a plurality of periods
(Period) divided by time intervals in a media presentation (Media
Presentation) as a whole MPD file. For example, the first period
starts from 0 seconds, the next period starts from 100 seconds, and
the like.
As illustrated in FIG. 2(b), there exists a plurality of adaptation
sets (AdaptationSet) in the period. Each adaptation set depends on
differences in media types such as videos and audio and differences
in languages, viewpoints, and the like in the same media type. As
illustrated in FIG. 2(c), there exists a plurality of
representations (Representation) in the adaptation set. Each
representation depends on stream attributes, for example,
differences in rates.
As illustrated in FIG. 2(d), the representation includes segment
info (SegmentInfo). As illustrated in FIG. 2(e), there exist an
initialization segment (Initialization Segment) and a plurality of
media segments (Media Segment) in this segment info. Information
for each of the segments (Segment) into which the period is further
finely divided is described in the media segments (Media Segment).
In the media segments, there exist address (url) information and
the like to actually obtain segment data such as videos and
audio.
Note that streams can be freely switched between the plurality of
representations included in the adaptation set. This configuration
allows selection of a stream with an optimum rate according to the
condition of the network environment on the reception side,
enabling seamless video distribution.
[Exemplary Configuration of the Transmission and Reception
System]
FIG. 3 illustrates an exemplary configuration of a transmission and
reception system 10 as an embodiment. This transmission and
reception system 10 includes a service transmission system 100 and
a service receiver 200. The service transmission system 100 in this
transmission and reception system 10 corresponds to the DASH stream
file server 31 and the DASH MPD server 32 in the stream
distribution system 30A illustrated in FIG. 1(a) described above.
Furthermore, the service transmission system 100 in this
transmission and reception system 10 corresponds to the DASH stream
file server 31, the DASH MPD server 32, and the broadcast
transmission system 36 in the stream distribution system 30B
illustrated in FIG. 1(b) described above.
Furthermore, the service receiver 200 in this transmission and
reception system 10 corresponds to the service receiver 33 (33-1,
33-2, . . . , and 33-N) in the stream distribution system 30A
illustrated in FIG. 1(a) described above. Furthermore, the service
receiver 200 in this transmission and reception system 10
corresponds to the service receiver 35 (35-1, 35-2, . . . , and
35-M) in the stream distribution system 30B illustrated in FIG.
1(b) described above.
The service transmission system 100 transmits DASH/MP4, that is, an
MPD file as a metafile, as well as MP4 including a media stream
(media segment) such as a video and audio through the communication
network transmission line (see FIG. 1(a)) or the RF transmission
line (see FIG. 1(b)).
"Exemplary Configuration of the Service Transmission System"
FIG. 4 illustrates an exemplary configuration of the service
transmission system 100. This service transmission system 100
includes a control unit 101, an HDR photoelectric conversion unit
103, an SDR photoelectric conversion unit 104, a dynamic range
conversion unit 105, a changeover switch 106, an RGB/YCbCr
conversion unit 107, a video encoder 108, a container encoder 109,
and a transmission unit 110.
The control unit 101 includes a central processing unit (CPU), and
controls the operation of each unit of the service transmission
system 100 on the basis of a control program. The HDR photoelectric
conversion unit 103 performs photoelectric conversion by applying
an HDR photoelectric conversion characteristic to a high contrast
camera output, that is, high dynamic range (HDR) video data Vh, and
obtains HDR transmission video data. This HDR transmission video
data becomes a video material produced as a video by an HDR
OETF.
The SDR photoelectric conversion unit 104 performs photoelectric
conversion by applying an SDR photoelectric conversion
characteristic to a standard contrast camera output, that is,
standard dynamic range (SDR) video data Vs, and obtains SDR
transmission video data. This SDR transmission video data becomes a
video material produced as a video by an SDR OETF.
The dynamic range conversion unit 105 obtains HDR transmission
video data by performing dynamic range conversion on the SDR
transmission video data. That is, this dynamic range conversion
unit 105 converts the SDR transmission video data, which is the
video material produced as the video by the SDR OETF, into the HDR
transmission video data. Here, the dynamic range conversion unit
105 performs the dynamic range conversion on the basis of
conversion information. The conversion information is for
converting a value of conversion data in accordance with the SDR
photoelectric conversion characteristic into a value of conversion
data in accordance with the HDR photoelectric conversion
characteristic. This conversion information is given, for example,
by the control unit 101.
The dynamic range conversion will be further described with
reference to FIG. 5. A solid line a indicates an example of an SDR
OETF curve indicating the SDR photoelectric conversion
characteristic. A solid line b indicates an example of an HDR OETF
curve indicating the HDR photoelectric conversion characteristic.
The horizontal axis indicates an input luminance level. P1
indicates an input luminance level corresponding to the SDR maximum
level. P2 indicates an input luminance level corresponding to the
HDR maximum level.
Furthermore, the vertical axis indicates a transmission code value
or a relative value of a normalized encoding level. A relative
maximum level M indicates the HDR maximum level and the SDR maximum
level. A reference level G indicates a transmission level of the
HDR OETF at the input luminance level P1 corresponding to the SDR
maximum level, which means a so-called white level as a reference.
It is indicated that the range higher than this level is used for
sparkling expression which is unique to HDR. A branch level B
indicates a level at which the SDR OETF curve and the HDR OETF
curve branch and separate from the same locus. Pf indicates an
input luminance level corresponding to the branch level. Note that
this branch level B can be any value equal to or greater than
0.
The SDR transmission video data from the branch level B to the
relative maximum level M is converted into a value of the
conversion data in accordance with the HDR photoelectric conversion
characteristic through the dynamic range conversion performed by
the dynamic range conversion unit 105. In this case, the relative
maximum level M which is the SDR maximum level is made to match the
reference level G. Note that the input data less than the branch
level B becomes output data as it is.
Here, the conversion information is given by a conversion table or
a conversion coefficient. In a case where the conversion
information is given by the conversion table, the dynamic range
conversion unit 105 performs the conversion by referring to this
conversion table. In contrast, in a case where the conversion
information is given by the conversion coefficient, the dynamic
range conversion unit 105 performs the conversion by making a
calculation using this conversion coefficient. For example, in a
case where the conversion coefficient is C, the input data from the
branch level B to the relative maximum level M is converted using
the following equation (1). Output data=branch level B+(input
data-branch level B)*C (1)
Referring back to FIG. 4, the changeover switch 106 selectively
takes out the HDR transmission video data obtained by the HDR
photoelectric conversion unit 103 or the HDR transmission video
data obtained by the dynamic range conversion unit 105. The
RGB/YCbCr conversion unit 107 converts the HDR transmission video
data taken out by the changeover switch 106 from an RGB domain to a
YCbCr (luminance and chrominance) domain. In this case, the
RGB/YCbCr conversion unit 107 performs the conversion using a
conversion equation corresponding to a color space on the basis of
color space information. Note that these color space domains are
not limited to the RGB domain, and the luminance and chrominance
domain is not limited to YCbCr.
The video encoder 108 performs encoding, for example, MPEG4-AVC or
HEVC on HDR transmission video data V1 which has been converted
into the YCbCr domain by the RGB/YCbCr conversion unit 107, and
obtains encoded video data. The video encoder 108 then generates a
video stream (video elementary stream) VS including this encoded
video data.
At this time, the video encoder 108 inserts meta-information into a
video usability information (VUI) area of an SPS NAL unit of an
access unit (AU). The meta-information indicates that the stream is
an HDR stream, and furthermore, an HDR electro-optical conversion
characteristic and the like. Furthermore, the video encoder 108
inserts a newly defined dynamic range conversion SEI message
(Dynamic_range_conv SEI message) into "SEIs" part of the access
unit (AU). The dynamic range conversion SEI message includes the
conversion information on the dynamic range conversion described
above. FIG. 6 illustrates an access unit located at the head of a
group of pictures (GOP) in a case where an encoding method is HEVC.
In the case of the HEVC encoding method, an SEI message group
"Prefix_SEIs" for decoding is arranged before a slice (slices)
where pixel data is encoded, and an SEI message group "Suffix_SEIs"
for display is arranged after this slice (slices). As illustrated
in the figure, the dynamic range conversion SEI message is arranged
as, for example, the SEI message group "Suffix_SEIs".
FIG. 7 illustrates an exemplary structure (Syntax) of the dynamic
range conversion SEI message. FIG. 8 illustrates contents
(Semantics) of the main information in the exemplary structure.
One-bit flag information of "Dynamic_range_conv_cancel_flag"
indicates whether a message of "Dynamic_range_conv" is refreshed.
"0" indicates that the message of "Dynamic_range_conv" is
refreshed. "1" indicates that the message of "Dynamic_range_conv"
is not refreshed. That is, the previous message is maintained as it
is.
In a case where "Dynamic_range_conv_cancel_flag" is "0", the
following fields exist. An 8-bit field of "coded_data_bit_depth"
indicates a bit depth of encoded pixels (bit depth of the
transmission code value). A 14-bit field of "reference_level"
indicates a reference luminance level value, that is, the reference
level G (see FIG. 5). One-bit flag information of
"ratio_conversion_flag" indicates that a simple conversion is
performed, that is, indicating that there exists a conversion
coefficient. One-bit flag information of "conversion_table_flag"
indicates that a conversion table is used, that is, indicating that
there exists conversion table information. A 16-bit field of
"branch_level" indicates the branch level B (see FIG. 5).
In a case where "ratio_conversion_flag" is "1", an 8-bit field of
"level_conversion_ratio" exists. This field indicates the
conversion coefficient (ratio of level conversion). In a case where
"conversion_table_flag" is "1", an 8-bit field of "table_size"
exists. This field indicates the number of inputs in the conversion
table. Then, "level_R[i]", "level_G[i]", and "level_B[i]" having
16-bit field each exists for the number of inputs. The "level_R[i]"
field indicates a value after conversion of a red component (Red
component). The "level_G[i]" field indicates a value after
conversion of a green component (Red component). The "level_B[i]"
field indicates a value after conversion of a blue component (Red
component).
Note that in a case where the bit depth of the encoded pixels is 8
bits, values corresponding to respective values of the input data
exist. However, in a case where the bit depth of the encoded pixels
is 10 bits, 12 bits or the like, only values corresponding to
respective values of high-order 8 bits of the input data exist. In
this case, when the conversion table is used on the reception side,
interpolated values are used for values of the remaining low-order
bits.
Referring back to FIGS. 1(a) and 1(b), the container encoder 109
generates a container, here MP4, as a distribution stream STM. The
container includes a video stream VS generated by the video encoder
108. Description will be given on a media file entity at a location
destination indicated by "<baseURL>" for a non-fragmented MP4
(Non-Fragmented MP4) case (VOD service).
In this case, it may be defined as "url 1" as illustrated in FIG.
9. In this case, an "ftyp" box is arranged first. The "ftyp" is
where a file type is described. Indicated by this "ftyp" box is a
non-fragmented MP4 file. Subsequently, a "moon" box and an "mdat"
box are arranged. The "moon" box includes all the metadata, for
example, header information of a track, meta description of
contents of the content, and time information. In the "mdat" box, a
SLICE NAL unit is arranged. The SLICE NAL unit is the media data
body. Note that each NAL unit of an SPS, a VPS, a PPS, and an SEI
can also be arranged in this "mdat" box.
Furthermore, each NAL unit of the SPS, the VPS, the PPS, and the
SEI is arranged in an "stsd" box under the "moon" box (method 1).
Meta-information of a video usability information (VUI) area of the
SPS NAL unit indicates, for example, that the stream is an HDR
stream. Furthermore, there also exists a NAL unit of the
above-described dynamic range conversion SEI message as an SEI NAL
unit. Note that elements defined by a "kind" box in the "udta" box
under the "moon" box may be used to indicate, for example, that the
stream is an HDR stream (method 2).
Furthermore, description will be given on a media file entity at a
location destination indicated by "<baseURL>" for a
fragmented MP4 (Fragmented MP4) case (multicast service).
In this case, it may be defined as "url 2" as illustrated in FIG.
10. In this case, an "styp" box is arranged first. The "styp" box
is where a file type is described. Subsequently, a "sidx" box is
arranged. The "sidx" box is where a segment index is described.
After that, a predetermined number of movie fragments (Movie
Fragment) are arranged.
Each movie fragment includes a "moon" box, a "moof" box, and an
"mdat" box. The "moof" includes fragment control information. The
"mdat" box includes media data body. The multicast service has to
be subjected to random access. To cope with the random access, it
is necessary to arrange the "moon" box in each movie fragment. This
configuration will be similarly applied to the broadcasting case
described later. In the "mdat" box, a SLICE NAL unit is arranged.
The SLICE NAL unit is the media data body. Note that each NAL unit
of an SPS, a VPS, a PPS, and an SEI can also be arranged in this
"mdat" box.
Furthermore, each NAL unit of the SPS, the VPS, the PPS, and the
SEI is arranged in an "stsd" box under the "moon" box (method 1).
Meta-information of a video usability information (VUI) area of the
SPS NAL unit indicates, for example, that the stream is an HDR
stream. Furthermore, there also exists a NAL unit of the
above-described dynamic range conversion SEI message as an SEI NAL
unit. Note that elements defined by a "kind" box in the "udta" box
under the "moon" box may be used to indicate, for example, that the
stream is an HDR stream (method 2).
Furthermore, description will be given on a media file entity for a
fragmented MP4 (Fragmented MP4) case (broadcasting). In this case,
an "styp" box is arranged first as illustrated in FIG. 11. The
"styp" box is where a file type is described. Subsequently, a
"sidx" box is arranged. The "sidx" box is where a segment index is
described. After that, a predetermined number of combinations of an
"MPD" box and a movie fragment (Movie Fragment) are arranged.
An MPD file is arranged in the "MPD" box. Each movie fragment
includes a "moon" box, a "moof" box, and an "mdat" box. The "moof"
includes fragment control information. The "mdat" box includes
media data body. In the "mdat" box, a SLICE NAL unit is arranged.
The SLICE NAL unit is the media data body. Note that each NAL unit
of an SPS, a VPS, a PPS, and an SEI can also be arranged in this
"mdat" box.
Furthermore, each NAL unit of the SPS, the VPS, the PPS, and the
SEI is arranged in an "stsd" box under the "moov" box (method 1).
Meta-information of a video usability information (VUI) area of the
SPS NAL unit indicates, for example, that the stream is an HDR
stream. Furthermore, there also exists a NAL unit of the
above-described dynamic range conversion SEI message as an SEI NAL
unit. Note that elements defined by a "kind" box in the "udta" box
under the "moon" box may be used to indicate, for example, that the
stream is an HDR stream (method 2).
Note that the MPD file can be considered to include the
meta-information in the above-described VUI area, dynamic
conversion information, and the like. In the MPD file,
"schemeIdUri" can be newly defined as broadcasting or any other
applications by "SupplementaryDescriptor", separately from an
existing definition in the conventional standard.
FIG. 12 illustrates an exemplary description of the MPD file.
Although the example illustrated herein describes only information
on video streams to simplify the description, information on media
streams other than the video streams is also described in practice.
FIG. 13 illustrates "Value" semantics of
"SupplementaryDescriptor".
The description of "<AdaptationSet mimeType="video/mp4"
group="1">" indicates that there exists an adaptation set
(AdaptationSet) for a video stream, the video stream is supplied
with an MP4 file structure, and a group 1 is allocated. The
description of "<SupplementaryDescriptor
schemeIdUri="urn:brdcst:codecType" value="hevc"/> indicates that
the codec of the video stream is "HEVC".
The description of <SupplementaryDesctiptor
schemeIdUri="urn:brdcst:video:highdynamicrange" value="HDR"/>
indicates that the current stream is an HDR stream. Note that "1"
may be described instead of "HDR" to indicate that the current
stream is an HDR stream. Furthermore, "SDR" or "0" is described to
indicate that the current stream is an HDR stream.
The description of <SupplementaryDesctiptor
schemeIdUri="urn:brdcst:video:transferfunction"
value="EOTFtype"/> indicates an electro-optical conversion
characteristic (EOTF characteristic). For example, in the case of
"BT.709-5 Transfer Function", "bt709" or "1" is described in the
"EOTFtype" part. Furthermore, for example, in the case of "10 bit
BT.2020 Transfer Function", "bt2020" or "14" is described in the
"EOTFtype" part. Furthermore, for example, in the case of "SMPTE
2084 Transfer Function", "st2028" or "16" is described in the
"EOTFtype" part.
The description of <SupplementaryDesctiptor
schemeIdUri="urn:brdcst:video:xycolourprimaries"
value="ColorGamut"/> indicates a color space. For example, in
the case of "BT.709-5", "bt709" or "1" is described in the
"ColorGamut" part. Furthermore, for example, in the case of
"BT.2020", "bt2020" or "9" is described in the "ColorGamut" part.
Furthermore, for example, in the case of "SMPTE 428 or XYZ",
"st428" or "10" is described in the "ColorGamut" part.
The description of <SupplementaryDesctiptor
schemeIdUri="urn:brdcst:video:matrixcoefficients"
value="ColorMatrix"/> indicates a color matrix coefficient. For
example, in the case of "BT.709-5", "bt709" or "1" is described in
the "ColorMatrix" part. Furthermore, for example, in the case of
"BT.2020 non-constant lumiinance", "bt2020n" or "9" is described in
the "ColorMatrix" part. Furthermore, for example, in the case of
"SMPTE 2085 or Y'D'zD'x", "st2085" or "11" is described in the
"ColorMatrix" part.
The description of <SupplementaryDesctiptor
schemeIdUri="urn:brdcst:video:referencelevel" value="RefLevel"/>
indicates the reference level G (see FIG. 5). A reference level
specified with a value of 0 to 100 in a relative range normalized
to "1" at maximum is described in the "RefLevel" part. A value
obtained by dividing this value by 100 is recognized as a relative
reference level on the reception side. This relative reference
level constitutes a conversion coefficient as conversion
information for the dynamic range conversion.
The description of <SupplementaryDesctiptor
schemeIdUri="urn:brdcst:video:branchlevel" value="BranchLevel"/>
indicates the branch level B (see FIG. 5). A branch level specified
with a value of 0 to 100 in a relative range normalized to "1" at
maximum is described in the "BranchLevel" part. A value obtained by
dividing this value by 100 is recognized as a relative reference
level on the reception side.
The description of <SupplementaryDesctiptor
schemeIdUri="urn:brdcst:video:streamdependency"
value="DependType"/> indicates whether the current stream is an
independent stream. In the case of an independent stream, "base" or
"0" is described in the "DependType" part. In the case of a
dependent stream, "extended" or "1" is described in the
"DependType" part.
The description of <SupplementaryDesctiptor
schemeIdUri="urn:brdcst:video:originaldynamicrange"
value="DrangeType"/> indicates whether original video data of
the current stream is SDR video data. In the case of SDR video
data, "sdr" is described in the "DrangeType" part. In the case of
HDR video data, "hdr" is described in the "DrangeType" part.
The description of "<Representation id="1"
bandwidth="20000000">" indicates that there exists a video
stream with a bit rate of 20 Mbps, which includes encoded data of
group 1 "group1" as a representation identified by "Representation
id="1"" in the adaptation set of the group 1. Then, the description
of "<baseURL>video/jp/20000000.mp4</BaseURL>" indicates
that a location destination of the video stream is
"video/jp/20000000.mp4".
The exemplary description of the MPD file in FIG. 12 is an example
in a case where a dependent stream exists. The description of
"<AdaptationSet mimeType="video/mp4" group="2">" indicates
that there exists an adaptation set (AdaptationSet) for a video
stream, the video stream is supplied with the MP4 file structure,
and a group 2 is allocated. Although detailed description is
omitted, information similar to that of the video stream of the
group 1 described above is also described for the video stream of
the group 2.
Note that the elements defined by the "kind" box in the "udta" box
under the "moon" box described above can be, for example, the
elements enclosed by a broken line frame in FIG. 12.
Referring back to FIG. 4, the transmission unit 110 transmits the
MP4 distribution stream STM, which has been obtained by the
container encoder 109, to the service receiver 200 on a broadcast
wave or in a network packet.
The operation of the service transmission system 100 illustrated in
FIG. 4 will be briefly described. HDR video data Vh, which is a
high contrast camera output, is supplied to the HDR photoelectric
conversion unit 103. In this HDR photoelectric conversion unit 103,
photoelectric conversion is performed on the HDR video data Vh on
the basis of an HDR photoelectric conversion characteristic, and
HDR transmission video data is obtained as a video material
produced as a video by an HDR OETF.
Furthermore, SDR video data Vs, which is a standard contrast camera
output, is supplied to the SDR photoelectric conversion unit 104.
In this SDR photoelectric conversion unit 104, photoelectric
conversion is performed on the SDR video data Vs on the basis of an
SDR photoelectric conversion characteristic, and SDR transmission
video data is obtained as a video material produced as a video by
an SDR OETF.
The SDR transmission video data obtained in the SDR photoelectric
conversion unit 104 is supplied to the dynamic range conversion
unit 105. In the dynamic range conversion unit 105, dynamic range
conversion is performed on the SDR transmission video data on the
basis of conversion information (conversion table, conversion
coefficient) supplied from the control unit 101. The SDR
transmission video data is converted into the HDR transmission
video data through this dynamic range conversion (see FIG. 5).
In the changeover switch 106, the HDR transmission video data
obtained in the HDR photoelectric conversion unit 103 or the HDR
transmission video data obtained in the dynamic range conversion
unit 105 is selectively taken out under control of the control unit
101. The HDR transmission video data taken out in this way is
converted from the RGB domain to the YCbCr (luminance and
chrominance) domain in the RGB/YCbCr conversion unit 107.
The HDR transmission video data V1 converted into the YCbCr domain
is supplied to the video encoder 108. In this video encoder 108,
encoding, for example, MPEG4-AVC or HEVC is performed on the HDR
transmission video data V1 to obtain encoded video data, through
which a video stream VS including this encoded video data is
generated.
In the video encoder 108, at this time, meta-information is
inserted into a video usability information (VUI) area of an SPS
NAL unit of an access unit (AU). The meta-information indicates
that the stream is an HDR stream, and furthermore, an HDR
electro-optical conversion characteristic, and the like. In the
video encoder 108, furthermore, a newly defined dynamic range
conversion SEI message is inserted into an "SEIs" part of the
access unit (AU). The dynamic range conversion SEI message includes
the conversion information (conversion cable, conversion
coefficient) on the dynamic range conversion (see FIG. 7).
The video stream VS obtained in the video encoder 108 is supplied
to the container encoder 109. In the container encoder 109, MP4
that is a container including the video stream VS is generated as a
distribution stream STM. At this time, meta-information is inserted
into MP4, for example, under the "moon" box. The meta-information
indicates, for example, that the stream is an HDR stream.
This distribution stream STM is transmitted by the transmission
unit 110 to the service receiver 200 on a broadcast wave or in a
network packet.
"Exemplary Configuration of the Service Receiver"
FIG. 14 illustrates an exemplary configuration of the service
receiver 200. This service receiver 200 includes a control unit
201, a reception unit 202, a container decoder 203, a video decoder
204, a YCbCr/RGB conversion unit 205, a changeover switch 206, an
HDR electro-optical conversion unit 207, a dynamic range inverse
conversion unit 208, and an SDR electro-optical conversion unit
209.
The control unit 201 includes a central processing unit (CPU), and
controls the operation of each unit of the service receiver 200 on
the basis of a control program. The reception unit 202 receives an
MP4 distribution stream STM transmitted from the service
transmission system 100 on a broadcast wave or in a network packet.
The container decoder 203 extracts a video stream VS from the MP4.
Furthermore, the container decoder 203 extracts meta-information
from the MP4 and transmits the meta-information to the control unit
201. The control unit 201 recognizes from this meta-information
that the stream is an HDR stream, as well as HDR electro-optical
conversion characteristic information, original video data
information, and the like.
The video decoder 204 performs decoding processing on the video
stream VS extracted by the container decoder 203, and obtains HDR
transmission video data V1. Furthermore, parameter sets and an SEI
message inserted into each access unit constituting the video
stream VS are extracted and transmitted to the control unit 201 by
the video decoder 204.
The control unit 201 recognizes from the meta-information in a VUI
area of an SPS NAL unit that the stream is an HDR stream, as well
as the HDR electro-optical conversion characteristic information,
and the like. Furthermore, the control unit 201 recognizes dynamic
range conversion information (conversion table, conversion
coefficient) from a dynamic range conversion SEI message.
The YCbCr/RGB conversion unit 205 converts the HDR transmission
video data V1, which has been obtained by the video decoder 204,
from the YCbCr (luminance and chrominance) domain to the RGB
domain. The changeover switch 206 transmits the HDR transmission
video data V1, which has been converted into the RGB domain, to the
HDR electro-optical conversion unit 207 or the dynamic range
inverse conversion unit 208 under control of the control unit
201.
In this case, in a case where a display monitor (not illustrated)
supports HDR, the changeover switch 206 transmits the HDR
transmission video data to the HDR electro-optical conversion unit
207. On the other hand, in a case where a display monitor supports
SDR, the changeover switch 206 transmits the HDR transmission video
data to the dynamic range inverse conversion unit 208.
The control unit 201 sets the HDR electro-optical conversion
characteristic in the HDR photoelectric conversion unit 207. The
HDR electro-optical conversion characteristic is the one recognized
from the meta-information, that is, the HDR electro-optical
conversion characteristic corresponding to an HDR photoelectric
conversion characteristic used on the transmission side. The HDR
photoelectric conversion unit 207 obtains display video data Vhd
for displaying an HDR image by applying the HDR electro-optical
conversion characteristic to the HDR transmission video data V1
taken out by the changeover switch 206.
The control unit 201 gives the dynamic range inverse conversion
unit 208, for example, the dynamic range conversion information
(conversion table, conversion coefficient) recognized from the
dynamic range conversion SEI message. The dynamic range inverse
conversion unit 208 performs, on the basis of this conversion
information, dynamic range inverse conversion on the HDR
transmission video data V1 which has been taken out by the
changeover switch 206, and obtains SDR transmission video data.
The details of the dynamic range inverse conversion will be
described with reference to FIG. 15. This is a case where original
video data of the current stream is SDR video data. The vertical
axis indicates an output luminance level, which corresponds to the
horizontal axis in FIG. 5. Furthermore, the horizontal axis
indicates a transmission code value, which corresponds to the
vertical axis in FIG. 5. A solid line a is an SDR EOTF curve
indicating an SDR electro-optical conversion characteristic. This
SDR EOTF curve corresponds to the SDR OETF curve indicated by the
solid line a in FIG. 5. A solid line b is an HDR EOTF curve
indicating an HDR electro-optical conversion characteristic. This
HDR EOTF curve corresponds to the HDR OETF curve indicated by the
solid line b in FIG. 5.
The HDR transmission video data from the branch level B to the
reference level G is converted so as to match a value of the
conversion data in accordance with the SDR photoelectric conversion
characteristic in the dynamic range inverse conversion performed by
the dynamic range inverse conversion unit 208. In this case, the
reference level G is made to match the relative maximum level M
which is the SDR maximum level. Note that the input data less than
the branch level B becomes output data as it is.
Here, the conversion information is given by the conversion table
or the conversion coefficient as described above. In a case where
the conversion information is given by the conversion table, the
dynamic range inverse conversion unit 208 performs the conversion
by referring to this conversion table. On the other hand, in a case
where the conversion information is given by the conversion
coefficient, the dynamic range inverse conversion unit 208 performs
the conversion by making a calculation using this conversion
coefficient. For example, in a case where the conversion
coefficient is C, the conversion is performed using the following
equation (2) with respect to the input data from the branch level B
to the reference level G. Output data=branch level B+(input
data-branch level B)*1/C (2)
Next, the details of the dynamic range inverse conversion will be
described with reference to FIG. 16. This is a case where original
video data of the current stream is HDR video data. In this case,
the input level to the HDR EOTF curve is converted into the input
level to the SDR EOTF curve by the dynamic range inverse conversion
unit 208. In FIG. 16, parts corresponding to those in FIG. 15 are
denoted by the same signs. Note that P1' indicates an output
luminance level corresponding to a predetermined level H lower than
the reference level G.
In this case, in the dynamic range inverse conversion performed by
the dynamic range inverse conversion unit 208, the input data up to
the predetermined level H lower than the reference level G is
converted in a similar manner to the above-described dynamic range
inverse conversion which is the case where the original video data
is SDR video data. Then, level conversion is performed on the input
data from the level H to the level M on the basis of a tone mapping
characteristic TM, through which output data is obtained. The tone
mapping characteristic TM is indicated by an alternate long and
short dashed line. In this case, the level H is converted into the
level H'', the reference level G is converted into the level G'',
and the level M is the level M as it is, for example.
By performing the level conversion on the input data from the level
H to the level M on the basis of the tone mapping characteristic TM
in this manner, it is possible to reduce deterioration in image
quality due to the level saturation from the reference level G to
the relative maximum level M.
The SDR electro-optical conversion unit 209 obtains display video
data Vsd for displaying an SDR image by applying the SDR
electro-optical conversion characteristic to the SDR transmission
video data obtained by the dynamic range inverse conversion unit
208.
The operation of the service receiver 200 illustrated in FIG. 14
will be briefly described. In the reception unit 202, an MP4
distribution stream STM transmitted from the service transmission
system 100 on a broadcast wave or in a network packet is received.
This distribution stream STM is supplied to the container decoder
203. In the container decoder 203, a video stream VS is extracted
from the MP4. In the container decoder 203, furthermore,
meta-information is extracted from the MP4, and transmitted to the
control unit 201. The control unit 201 recognizes from this
meta-information that the stream is an HDR stream, as well as HDR
electro-optical conversion characteristic information, original
video data information, and the like.
The video stream VS extracted in the container decoder 203 is
supplied to the video decoder 204. In the video decoder 204,
decoding processing is performed on the video stream VS, through
which HDR transmission video data V1 is obtained. In the video
decoder 204, furthermore, parameter sets and an SEI message
inserted into each access unit constituting the video stream VS are
extracted and transmitted to the control unit 201.
The control unit 201 recognizes from the meta-information in a VUI
area of an SPS NAL unit that the stream is an HDR stream, as well
as the HDR electro-optical conversion characteristic information,
and the like. Furthermore, dynamic range conversion information
(conversion table, conversion coefficient) is recognized from a
dynamic range conversion SEI message.
In the YCbCr/RGB conversion unit 205, the HDR transmission video
data V1 obtained in the video decoder 204 is converted from the
CbCr (luminance and chrominance) domain to the RGB domain. In a
case where a display monitor supports HDR, the HDR transmission
video data V1 converted into the RGB domain is supplied to the HDR
electro-optical conversion unit 207 through the changeover switch
206.
In the HDR photoelectric conversion unit 207, the HDR
electro-optical conversion characteristic is applied to the HDR
transmission video data V1, through which display video data Vhd
for displaying an HDR image is obtained. After display mapping
processing is appropriately performed on this display video data
Vhd according to the display capability of the display monitor, the
display video data Vhd is supplied to the display monitor and the
HDR image is displayed.
On the other hand, in a case where the display monitor supports
SDR, the HDR transmission video data V1 converted into the RGB
domain is supplied to the dynamic range inverse conversion unit 208
through the changeover switch 206. The dynamic range conversion
information (conversion table, conversion coefficient) is given to
the dynamic range inverse conversion unit 208 by the control unit
201 In the dynamic range inverse conversion unit 208, dynamic range
inverse conversion is performed on the HDR transmission video data
V1 on the basis of this conversion information, which is then
converted into SDR transmission video data (see FIG. 15). Note that
these color space domains are not limited to the RGB domain, and
the luminance and chrominance domain is not limited to YCbCr.
This SDR transmission video data is supplied to the SDR
electro-optical conversion unit 209. In the SDR electro-optical
conversion unit 209, the SDR electro-optical conversion
characteristic is applied to the SDR transmission video data,
through which display video data Vsd for displaying an SDR image is
obtained. After display mapping processing is appropriately
performed on this display video data Vsd according to the display
capability of the display monitor, the display video data Vsd is
supplied to the display monitor and the SDR image is displayed.
As described above, the SDR transmission video data which is the
video material produced as the video by the SDR OETF is transmitted
after being converted into the HDR transmission video data in the
transmission and reception system 10 illustrated in FIG. 3. Even
when transmitting the SDR video data, therefore, the reception side
can perform similar processing to that in the transmission of the
HDR video data. This makes it possible to simplify the
reception-side processing which is performed in a case where
transmission of the SDR video data and transmission of the HDR
video data are alternately performed.
Furthermore, the dynamic range conversion information (conversion
cable, conversion coefficient) is inserted into the video stream or
the container and transmitted in the transmission and reception
system 10 illustrated in FIG. 3. The dynamic range conversion
information is for converting the value of the conversion data in
accordance with the SDR photoelectric conversion characteristic
into the value of the conversion data in accordance with the HDR
photoelectric conversion characteristic. The use of this conversion
information, therefore, allows the reception side to easily perform
processing for converting the HDR transmission video data into the
SDR transmission video data and displaying the SDR image.
2. Modification
Note that although not described above, in a case where values of
"reference_level", "branch_level", and "level_conversion_ratio"
that are premised in the present technology are fixedly defined on
the transmission and reception sides, the service receiver 200 may
be a receiver that has a function of performing a similar level
conversion with respect to received data in a distribution where
the values described above are guaranteed in advance even if these
elements are not transmitted.
Furthermore, the embodiment described above illustrates an example
in which the container is MP4. However, the present technology is
not limited to MP4, and may also be similarly applicable to
containers in any other formats such as MPEG-2 TS and MMT.
For example, in the case of MPEG-2 TS, a transport stream TS
including a video stream VS is generated in the container encoder
109 of the service transmission system 100 illustrated in FIG.
4.
At this time, meta-information indicating, for example, that the
stream is an HDR stream is inserted into the transport stream TS in
the container encoder 109. For example, the container encoder 109
inserts a dynamic range conversion descriptor
(Dynamic_range_conversion descriptor) under a program map table
(Program Map Table (PMT)).
FIG. 17 illustrates an exemplary structure (Syntax) of the dynamic
range conversion descriptor. FIG. 18 illustrates the contents
(Semantics) of the main information in the exemplary structure. An
8-bit field of "descriptor_tag" indicates a descriptor type.
Indicated here is a high dynamic range descriptor. An 8-bit field
of "descriptor_length" indicates the length (size) of the
descriptor, which indicates the number of subsequent bytes as the
length of the descriptor.
An 8-bit field of "highdynamicrange" indicates whether the current
stream is an HDR stream. "1" indicates an HDR stream, and "0"
indicates an SDR stream. An 8-bit field of "transferfunction"
indicates an electro-optical conversion characteristic (EOTF
characteristic). For example, "1" indicates "BT.709-5 Transfer
Function", "14" indicates "10 bit BT.2020 Transfer Function", and
"16" indicates "SMPTE 2084 Transfer Function".
An 8-bit field of "xycolourprimaries" indicates a color space. For
example, "1" indicates "BT.709-5", "9" indicates "BT.2020", and
"10" indicates "SMPTE 428 or XYZ". An 8-bit field of
"matrixcoefficients" indicates a color matrix coefficient. For
example, "1" indicates "BT.709-5", "9" indicates "BT.2020
non-constant lumiinance", and "11" indicates "SMPTE 2085 or
Y'D'zD'x".
An 8-bit field of "referencelevel" indicates the reference level G
(see FIG. 5). In this case, a value specified with a value of 0 to
100 in a relative range normalized to "1" at maximum is described
as the reference level G. A value obtained by dividing this value
by 100 is recognized as a relative reference level on the reception
side. This relative reference level constitutes a conversion
coefficient as conversion information for the dynamic range
conversion.
An 8-bit field of "branchlevel" indicates the branch level B (see
FIG. 5). In this case, a value specified with a value of 0 to 100
in a relative range normalized to "1" at maximum is described as
the branch level B. A value obtained by dividing this value by 100
is recognized as a branch level on the reception side.
A 4-bit field of "streamdependency" indicates whether the current
stream is an independent stream. For example, "0" indicates an
independent stream, and "1" indicates a dependent stream. A 4-bit
field of "originaldynamicrange" indicates whether original video
data of the current stream is SDR video data. For example, "0"
indicates SDR video data, and "1" indicates HDR video data.
FIG. 19 illustrates an exemplary configuration of the transport
stream TS. In this exemplary configuration, there exists a PES
packet "video PES1" of a video stream identified by PID1.
Meta-information is inserted into a VUI area of an SPS of an access
unit. The meta-information indicates that the stream is an HDR
stream, as well as an HDR electro-optical conversion
characteristic, and the like. Furthermore, a dynamic range
conversion SEI message is inserted into the access unit. Dynamic
range conversion information is described in the dynamic range
conversion SEI message.
Furthermore, the transport stream TS includes a program map table
(PMT) as program specific information (PSI). The PSI is information
describing which program each elementary stream included in the
transport stream belongs to. In the PMT, there exists a program
loop (Program loop) that describes information related to the
entire program.
In the PMT, there exists an elementary stream loop having
information related to each elementary stream. In this exemplary
configuration, there exists a video elementary stream loop (video
ES loop) corresponding to the video stream. Not only is information
such as a stream type and a packet identifier (PID) arranged
corresponding to the video stream, but also a descriptor describing
information related to the video stream is arranged in the video
elementary stream loop (video ES loop).
A value of "Stream_type" of this video stream is set to a value
indicating, for example, an HEVC video stream. The PID information
indicates PID1 added to a PES packet "video PES" of the video
stream. A dynamic range conversion descriptor is inserted as one of
the descriptors.
Furthermore, the present technology can also have a configuration
as follows.
(1) A transmission apparatus including:
a dynamic range conversion unit configured to obtain high dynamic
range transmission video data by performing dynamic range
conversion on standard dynamic range transmission video data on the
basis of conversion information for converting a value of
conversion data in accordance with a standard dynamic range
photoelectric conversion characteristic into a value of conversion
data in accordance with a high dynamic range photoelectric
conversion characteristic, the standard dynamic range transmission
video data being obtained by performing, on standard dynamic range
video data, photoelectric conversion in accordance with the
standard dynamic range photoelectric conversion characteristic;
an encoding unit configured to obtain a video stream by performing
encoding processing on the high dynamic range transmission video
data; and
a transmission unit configured to transmit a container having a
predetermined format and including the video stream.
(2) The transmission apparatus according to (1) above, further
including:
an information insertion unit configured to insert the conversion
information into the video stream and/or the container.
(3) The transmission apparatus according to (2) above,
in which the information insertion unit further inserts, into the
container, information indicating that the video stream supports a
high dynamic range.
(4) The transmission apparatus according to (2) or (3) above,
in which the information insertion unit further inserts, into the
container, information indicating a high dynamic range
electro-optical conversion characteristic corresponding to the high
dynamic range photoelectric conversion characteristic.
(5) The transmission apparatus according to any one of (2) to (4)
above,
in which the information insertion unit further inserts, into the
container, information indicating that original video data is the
standard dynamic range video data.
(6) The transmission apparatus according to any one of (1) to (5)
above,
in which the conversion information is of a conversion
coefficient.
(7) The transmission apparatus according to any one of (1) to (5)
above,
in which the conversion information is of a conversion table.
(8) A transmission method including:
a dynamic range conversion step of obtaining high dynamic range
transmission video data by performing dynamic range conversion on
standard dynamic range transmission video data on the basis of
conversion information for converting a value of conversion data in
accordance with a standard dynamic range photoelectric conversion
characteristic into a value of conversion data in accordance with a
high dynamic range photoelectric conversion characteristic, the
standard dynamic range transmission video data being obtained by
performing, on standard dynamic range video data, photoelectric
conversion in accordance with the standard dynamic range
photoelectric conversion characteristic;
an encoding step of obtaining a video stream by performing encoding
processing on the high dynamic range transmission video data;
and
a transmission step of transmitting, by a transmission unit, a
container having a predetermined format and including the video
stream.
(9) A reception apparatus including:
a reception unit configured to receive a container having a
predetermined format and including a video stream obtained by
encoding high dynamic range transmission video data;
a decoding unit configured to obtain the high dynamic range
transmission video data by performing decoding processing on the
video stream;
a dynamic range conversion unit configured to obtain standard
dynamic range transmission video data by performing dynamic range
conversion on the high dynamic range transmission video data
obtained by the decoding unit; and
an electro-optical conversion unit configured to obtain display
standard dynamic range video data by performing, on the standard
dynamic range transmission video data, electro-optical conversion
in accordance with a standard dynamic range electro-optical
conversion characteristic, the standard dynamic range transmission
video data being obtained by the dynamic range conversion unit.
(10) The reception apparatus according to (9) above,
in which the high dynamic range transmission video data obtained by
the decoding unit is obtained by performing dynamic range
conversion processing on the standard dynamic range transmission
video data on the basis of conversion information for converting a
value of conversion data in accordance with a standard dynamic
range photoelectric conversion characteristic into a value of
conversion data in accordance with a high dynamic range
photoelectric conversion characteristic, the standard dynamic range
transmission video data being obtained by performing, on standard
dynamic range video data, photoelectric conversion in accordance
with the standard dynamic range photoelectric conversion
characteristic.
(11) The reception apparatus according to (9) or (10) above,
in which conversion information is inserted into the video stream
and/or the container,
a conversion information extraction unit configured to extract the
conversion information from the video stream and/or the container
is further included, and
the dynamic range conversion unit performs the dynamic range
conversion on the basis of the conversion information extracted by
the conversion information extraction unit.
(12) A reception method including:
a reception step of receiving, by a reception unit, a container
having a predetermined format and including a video stream obtained
by encoding high dynamic range transmission video data;
a decoding step of obtaining the high dynamic range transmission
video data by performing decoding processing on the video
stream;
a dynamic range conversion step of obtaining standard dynamic range
transmission video data by performing dynamic range conversion on
the high dynamic range transmission video data obtained by the
decoding step; and
an electro-optical conversion step of obtaining display standard
dynamic range video data by performing, on the standard dynamic
range transmission video data, electro-optical conversion in
accordance with a standard dynamic range electro-optical conversion
characteristic, the standard dynamic range transmission video data
being obtained by the dynamic range conversion step.
A main feature of the present technology is to simplify
reception-side processing performed in a case where transmission of
SDR video data and transmission of HDR video data coexist in a time
sequence. This is achieved by converting SDR transmission video
data, which is a video material produced as a video by an SDR OETF,
into HDR transmission video data and transmitting the HDR
transmission video data (see FIGS. 4 and 5).
REFERENCE SIGNS LIST
10 Transmission and reception system 30A, 30B MPEG-DASH-based
stream distribution system 31 DASH stream file server 32 DASH MPD
server 33, 33-1 to 33-N Service receiver 34 CDN 35, 35-1 to 35-M
Service receiver 36 Broadcast transmission system 100 Service
transmission system 101 Control unit 103 HDR photoelectric
conversion unit 104 SDR photoelectric conversion unit 105 Dynamic
range conversion unit 106 Changeover switch 107 RGB/YCbCr
conversion unit 108 Video encoder 109 Container encoder 110
Transmission unit 200 Service receiver 201 Control unit 202
Reception unit 203 Container decoder 204 Video decoder 205
YCbCr/RGB conversion unit 206 Changeover switch 207 HDR
electro-optical conversion unit 208 Dynamic range inverse
conversion unit 209 SDR electro-optical conversion unit
* * * * *